The ability to plant nukes in enemy Cities is the most nefarious and powerful act a Spy or Cyber Ninja can perform. There is a 25% chance of success for the Spy, and a 35% chance of success for the Cyber Ninja. The risk of capture is significant - 75% for the Spy and 50% for the Cyber Ninja.
If the attack is successful, the nuke detonates, destroying the target city and all Tile Improvements within three tiles of the city. As with standard nukes, the affected area is reduced to dead tiles.
This attack constitutes an Atrocity. In addition, if the Spy or Cyber Ninja are caught attempting to plant a nuke, it is also considered an Atrocity. Use this attack with extreme caution.